Die for cold drawing

ABSTRACT

A die and method for cold drawing of metal wire, the die having a substantially circular passage extending throughout its length and tapering from an inlet to an outlet, there being at least three spaced apart grooves extending spirally about the passage and intervened by an arcuate surface of the passage. The grooves are of substantially the same cross section at the inlet and outlet ends of the die. This application is a continuing divisional application on applicant&#39;&#39;s copending U.S. application, Ser. No. 808,594, filed Mar. 19, 1969.

United States Patent [1 1 Ivanier [ll] 3,713,323 1 Jan. 30, 1973 [541DIE FOR COLD DRAWING [76] Inventor: lsin lvanler, 5509 Westbourne,

Montreal, Quebec, Canada [22] Filed: 0ct.2l, 1970 [2]] Appl. No.: 82,748

Related U.S. Application Data [62] Division Qrser. bio/808,594, Marchl9, I969. [30] Foreign Application Priority Data Mar. 18, I969 Canada..46. 097 Oct. 30, 1969 Great Britain ..5i, 544/69 [52] U.S. Cl...72/467, 72/274 [51] Int. Cl. ..B2lc 3/00, B2lc 1/00 [58] Field ofSearch ..72/467, 274, 293, 343

[56] References Cited UNITED STATES PATENTS 2,928,528 3/1960 Kelday..72/467 Primary Examiner-Richard J; Her b st Assistant Examiner-R. M.Rogers Attorney-Alan Swabey ABSTRACT A die and method for cold drawingof metal wire, the die having a substantially circular passage extendingthroughout its length and tapering from an inlet to an outlet, therebeing at least three spaced apart grooves extending spirally about thepassage and intervened by an arcuate surface of the passage. The groovesare of substantially the same cross section at the inlet an outlet endsof the die.

6 Claims, 10 Drawing Figures SHEET 1 or 2 FIG. 2

FIG I n l 2 T m INVENTOR Isin IVANIER PAIENIEDmso 191s 3.713.323

saw 2 or 2 v 'INVENTOR Isin IVANIER ATTORNEY DIE FOR COLD DRAWING Thisapplication is a continuing divisional application on applicant'scopending U.S. application, Ser. No. 808,594, filed Mar. 19, 1969.

BACKGROUND OF THE INVENTION a. Field of the Invention This inventionrelates to the production of cold drawn screw type wire, and nails orscrews made therefrom. In a still further aspect, this invention relatesto a novel die used in carrying out the process of the present inventionto produce these products; and in a still further aspect, to'a devicefor forming the novel die.

b. Description of Prior Art U.S. Pat. No. 946,631 Ballou (1910) and U.S.Pat. No. 2,928,528 Kelday et al. (1960) describe the cold drawing ofmetal wire. The latter patent discloses the cold drawing of wire througha rotatable die which has a passage of gradually diminishingcross-sectional area throughout a substantial part of its workinglength. The passage has a general cross-sectional shape which isnon-circular over at least a substantial portion of its working lengthand is helically twisted about its longitudinalaxis throughout saidportion of non-circular cross-sectional shape, so that a wire drawn bythe die has crests and valleys in which the grain flow lines runlongitudinally across the valleys in the direction of the longitudinalaxis of the wire. The resulting article has desirable characteristicsimparted by the cold drawing operation and other advantages aselaborated in the Kelday et a]. patent. The surface of the drawnarticle, that is the wire or nails made from it, is essentially providedwith helical flat or concave flutes intervened by lands.

SUMMARY OF INVENTION Wire according to the present invention is alsocold drawn through a rotatable die. But the die of the invention hasspecial characteristics differing from those of the prior art die aswill be explained and understood in terms of the wire produced. Thewire, as drawn, has a core of overall circular cross-section andintegrally standing out from it, in equally spaced apart relationship,at least three helically extending ribs. Adjacent ribs are intervened byconvex surfaces of the core, which on a trans-axial cross-sectionthrough the wire,

are arcuate. v

In a preferred construction, each rib tapers from a relatively bluntroot to a tip which may be sharp or slightly rounded, for example havinga radius of not more than about five thousandths of an inch. Preferably,the root of each rib is not less than one third and not greater thanequal to the length of the arcuate surface of the core between adjacentribs. Preferably, the height of each rib is at least as great and notmore than twice the width of its root.

The wire may be drawn through a die of special construction which is anaspect of the invention. The die is made using a reamer which is also anaspect of the invention. The reamer has essentially the configuration ofthe wire described above, except that it is tapered for the purpose ofconforming to the tapered opening in the die when the latter is beingfashioned. The tips of its ribs are preferably sharp. The reamed die hasan opening, tapering to a narrower dimension from the entrance to theexit end and helical grooves complementary to the ribs of the reamer andarcuate surfaces intervening the grooves.

The wire may be drawn by the use of the die, in accordance with anotheraspect of the invention, as follows. The die is held in a manner wellknown, permitting it to rotate freely as the wire is drawn through thehelically grooved working opening. In the drawing process, the wireimmediately comes into contact with the grooved working surface andstays in contact with it until leaving the die. It is a feature of themethod of the invention that wire emerging from the grooved die has anoutside diameter markedly greater than the outside diameter of the wireas it enters the die. The working surface of the die of the invention islonger than usual for a die for making fluted wire as in the aforesaidKelday et al. patent.

BRIEF DESCRIPTION OF DRAWINGS Having thus generally described the natureof the invention, it will be referred to in greater detail by referenceto the accompanying drawings, which illustrate preferred embodiments andin which:

FIG. 1 is a side elevation of a reamer used to make a die for drawingwire according to the invention;

FIG. 2 is an enlarged cross-section on the line 2-2 of FIG. 1;

FIG. 3 is an end view illustrating a manner of forming the reamer,showing forming tools in contact with a partly formed reamer;

FIG. 4 is an entrance end view of a die according t the invention; I

FIG. 5 is a longitudinal cross-section through the die of FIG. 4;

FIG. 6 is a side elevation of helically ribbed wire as cold drawnaccording to the invention;

FIG. 7 is an enlarged cross-section through a four ribbed wire accordingto the invention;

FIG. 8 is a pair of views (side elevation and head plan view,respectively) showing a screw type nail;

FIG. 9 is a pair of views similar to those vof FIG. 8 showing a screwwith a slotted head;

FIG. 10 is a pair of views similar to those of FIGS. 8 and 9 showing ascrew having a recessed head.

DESCRIPTION OF PREFERRED EMBODIMENTS Incarrying out the invention, areamer of a special form is made from tool steel. One form is shown inFIGS. 1 and 2. The forming tool shown, by way of example, has six ribs,but it should be understoodthat the number of ribs can be anywhere fromthree or more and can go up to 15 or more, depending on the size of thewire and the gauge of the wire to be cold drawn, as will be explainedmore fully later. A preferred range is from three to nine ribs.

Referring to FIGS. 1 and 2, the reamer indicated generally as A isprovided with a shank l5 and a work ing part 17. The part 17 has a coreof overall circular cross-section and tapers from the junction with theshank 15 to its free end (the arcuate surfaces 19) with integralprotruding ribs 22. The ribs 22 and the intervening arcuate (on asection normal to the axis of the body) parts 19 extend helically thelength of the working part 17.

The reamer A is formed from a piece of cylindrical tool steel stock. InFlG. 3 on the left-hand side of the drawing, a fraser B is shown incontact with the tip ofa partly finished tool and at the right-hand sideof the drawing, a forming tool B is shown in contact with the wider endof the partially finished tool. FIG. 3 is actually an end view of theforming tool looking from the tapered end. The forming tool runs up anddown the stock and at the same time the stock turns about its axis sothat the forming tool describes a helical path along the stock andgradually shaves the stock cutting it away along predetermined stripsand leaving the ribs 22 intervened by the arcuate surfaces 19. For everydiameter of wire and/or number of ribs a different sized forming toolwill have to be used to appropriately fashion the reamer.

The reamer is used to form the die by pushing the reamer in and out ofthe die opening of starting circular cross-section tapering fromentrance to exit, using a special machine, as is understood by diemakers.

The die is shown as C and it has an overall tapering passage 31. Inaccordance with the invention, there are reamed out grooves 33intervening ungrooved arcuate surfaces 35. The die is made of a suitablehard or hardened material such as hardened tool steel or other materialfrom which wire drawing dies are made. The difference in the use of thedie C, from the use of dies as known, is that the wire that enters thedie is not of a greater diameter than the wire that leaves the die, but,on the contrary, the wire entering the die has a smaller diameter andcomes out having a larger outside diameter (measured to the tips of theribs 22). The die C is mounted for free rotation in a unit in which itis held in ball bearings to allow for its free rotation by the drawingaction. ln the drawing operation, the usual lubricants for cold drawingof metal wires may be employed.

In the drawing operation, the wire is preferably first reduced from alarger diameter to a desired smaller diameter by passing it through apreliminary drawing operation in a normal die having a circularcross-section, and, then immediately passing it through a die groovedaccording to the invention. The wire entering the grooved die has anoutside diameter less than the overall diameter (tip to tip of ribs) ofthe ribbed wire leaving the grooved die.

A typical wire resulting from the drawing operation according to theinvention is shown in FIGS. 6 and 7. The wire has a core D of circularcross-section and upstanding integral ribs 41 which run helically alongthe core D, intervened by arcuate surfaces 45 extending helically alongand about the core D. The wire can have three or more ribs with three tonine preferred. The

Typical nails and screws are shown in FIGS. 8 to 10. In the case ofeither the nail or the screw, it can be driven without a screwdriver,simply by hammering. However,

in its removal a screwdriver maybe usedas for a screw or it can beforced out like a nail.

The taper of the reamer and of the working opening in the die may befrom 1 to l2 from the die axis depending on the diameter of wire to bedrawn. According to the invention, the groove and intervening ungroovedsurfaces preferably extend the entire working grooves of the opening inthe tool steel insert of the die, so that the'wire entering the dieimmediately comes into contact with the grooved portion of the die andthe wire leaving the die leaves from a grooved portion of the die.

Metals which may be cold drawn according to the invention are any typeof metal or alloy normally used for cold drawing, for example steel,aluminum and its alloys, bronze, phosphor bronze, copper or brass. Steelis the most common. The direction of the spiral ribs on the nails or thescrews can be either righthand or lefthand.

One advantage of the invention is that screws can be made which can besubstituted for those normally made by roll-threading. The nails of theinvention have higher strength, for the same diameter, than nails of thefluted type. This means that a larger quantity of the product isavailable from the same weight of metal. The holding power of theproduct of the invention is markedly greater than the holding power of afluted product of the same gauge.

Theoretically, the gauge of the wire which can be drawn is unlimited.The preferred gauges are from 14 gauge up to wires of a diameter of oneinch and more. The preferred number of ribs may vary from three to nine,the maximum number of ribs being limited by the diameter of the wire.The width of the rib at the root can be anywhere from one to one thirdthe length of the are between the roots of respective ribs. As forpitch, this can range from four to .17 turns per inch.

Table 1 gives a representative range of gauges, namely preferred rangesof external diameters, internal diameters, height of. ribs, number ofribs, ranges of pitch, and desirable relationships between thesequantitative factors. The linear dimensions are expressed in inches.Taking for example a 5 gauge wire, the external diameter (meaning tip totip) would be 0.212 inches. The preferred ranges would be: number ofribs 3 to 6; a core diameter of from about 0.106 to about 0.140 inches;height of ribs from about 0.35 to 0.053, and pitch from about-.83 toabout .4 turns per inch. The height of each rib is measured from its tipor crest to the intersection of a line from the tip or crestperpendicular to the core axis with a line representing an extension ofthe arcuate surface of the core.

TABLE I (PREFERRED RANGES) Gauge External Range of Range for NumberRange Diameter* Core Height of of Ribs of Pitch (ins diameter Ribs(turns/in.)

' (ins.) (ins.)

7/0 .500 .250.375 .062-.l25 3-9 .33 .17 6/0 .464 .232-.348 .058.l l6 3-9.37 .18 5/0 .432 .2l6.324 .054-. l08 3-9 .42 .l9 4/0 .400 .200.300.050-.l00 3-9 .045 .2l 3/0 .372 .l86.279 .046.093 3-9 .5 .22 00 .348.l74.26l .043.087 3-9 .56 .24 0 .324 .l62.243 .040-.08l 3-9 .59 .26 l.300 .l50-.225 .037-.075 3-9 .62 .28 2 .276 .l38 -.207 .035-.069 3-9 .67.3 3 I .252' .l26.l84 .035.063 3-8 .71 .33 4 .232 .l 16-.162 .035.058-3-7 .77 .37 5 .212 .l06-. l40 .O35.053 3-6 .83 .4

" As measured tip to tip of ribs.

I claim:

- has a taper of 1 to 12.

3. A die as defined in claim 1, wherein each said groove issubstantially triangular in shape and has a root, and wherein the rootdimension of said cross-sectional shape at said inlet is about equal tothe root dimension of said cross-sectional shape at said outlet.

4. A die for cold drawing metal wire as defined in claim 1, wherein thewidth of each groove between its adjacent concave surfaces is in therange of l to 1/3 the arcuate distance on each of said concave surfacesbetween adjacent of said grooves.

5. A die for cold drawing metal wire as defined in claim 2, wherein thewidth of each groove between its adjacent concave surfaces is in therange of l to 1/3 the arcuate distance on each of said concave surfacesbetween adjacent of said grooves.

6. A die for cold drawing metal wire as defined in claim 3, wherein thewidth of each groove between its adjacent concave surfaces is in therange of l to 1/3 the arcuate distance on each of said concave surfacesbetween adjacent of said grooves.

* l l it l

1. A die for cold drawing metal wire comprising, a die body having a drawing passage of substantially circular cross-section throughout its length and tapering from an inlet to an outlet, at least three equally spaced apart grooves extending spirally about said passage with adjacent grooves intervened by a concave surface of said passage, said grooves being of substantially the same cross-secTional shape at said inlet and said outlet and extending the full working length of said die.
 1. A die for cold drawing metal wire comprising, a die body having a drawing passage of substantially circular cross-section throughout its length and tapering from an inlet to an outlet, at least three equally spaced apart grooves extending spirally about said passage with adjacent grooves intervened by a concave surface of said passage, said grooves being of substantially the same cross-secTional shape at said inlet and said outlet and extending the full working length of said die.
 2. A die as defined in claim 1, wherein said passage has a taper of 1* to 12* .
 3. A die as defined in claim 1, wherein each said groove is substantially triangular in shape and has a root, and wherein the root dimension of said cross-sectional shape at said inlet is about equal to the root dimension of said cross-sectional shape at said outlet.
 4. A die for cold drawing metal wire as defined in claim 1, wherein the width of each groove between its adjacent concave surfaces is in the range of 1 to 1/3 the arcuate distance on each of said concave surfaces between adjacent of said grooves.
 5. A die for cold drawing metal wire as defined in claim 2, wherein the width of each groove between its adjacent concave surfaces is in the range of 1 to 1/3 the arcuate distance on each of said concave surfaces between adjacent of said grooves. 